Disc-type variable reluctance rotating machine

ABSTRACT

Described is a novel design for a disc-type variable reluctance rotating machine. The rotating machine, preferably used as a motor, is brushless and in the preferred form comprises a plurality of stator discs that are supported by a frame including a pair of spaced and parallel end plates. A shaft is rotatably journaled in the end plates and the stator discs are separated from one another by a plurality of rotor discs attached to the shaft for rotation therewith. The stator discs each have an annular channel in which a helically wound winding is positioned. Each of the stator discs also includes a plurality of equally spaced inner and outer inserts made from a magnetic material. The rotor discs also have inserts made from magnetic material to form a flux path around the winding in each of the stator discs. The rotating machine of the invention may be operated as an AC synchronous machine or as a pulsed-current variable speed machine.

United States Patent Helntz [S4] DISC-TYPE VARIABLE RELUCTANCE ROTATINGMACHINE Colgate ..3 10/268 1 5] Oct. 24, 1972 [57] ABSTRACT Described isa novel design for a disc-type variable reluctance rotating machine. Therotating machine, preferably used as a motor, is brushless and in thepreferred form comprises a plurality of stator discs that are supportedby a frame including a pair of spaced and parallel end plates. A shaftis rotatably joumaled in the end plates and the stator discs areseparated from one another by a plurality of rotor discs attached to theshaft for rotation therewith. The stator discs each have an annularchannel in which a helically wound winding is positioned. Each of thestator discs also includes a plurality of equally spaced inner and outerinserts made from a magnetic material. The rotor discs also have insertsmade from magnetic material to form a flux path around the winding ineach of the stator discs. The rotating machine of the invention may beoperated as an AC synchronous machine or as a pulsed-current variablespeed machine.

9 Claims, 4 Draw1ng Figures PATENTED um 24 1912 SHEET 1 BF 2 PATENTEDncI24 I972 SHEET 2 0F 2 -2 FIG.3

DISC-TYPE VARIABLE RELUCTANCE ROTATING MACHINE BACKGROUND OF THEINVENTION This invention relates to disc-type variable reluctancerotating machines. More particularly, the invention relates to a novelconstruction for a machine of this type.

Disc-type variable reluctance rotating machines are well known in theprior art. The construction and operation of a known design of areluctance motor, together with various control circuits for suchmotors, may be seen in U.S. Pat. Nos. 3,560,817 and 3,560,818, issuedFeb. 2, 1971, to C. J. Amato, and in U.S. Pat. No. 3,560,820, issuedFeb. 2, 19-71, in the name of L. E. Unnewehr. Additional controlcircuits for motors of this type may be seen in U.S. Pat. applicationSer. Nos. 121,653 and 121,654, filed in the name of L. E. Unnewehr,121,655, filed in the name of D. R. Hamburg, and 121,656, filed in thename of W. H. Koch, all of the foregoing U.S. Pat. applications havingbeen filed March 8, 1971, andassigned to the Ford Motor Company.

The motor described in the above-identified references is a three-phasemotor design. However, each of the phases is controlled in a similarmanner and the principle of operation is identical for all of thephases. The various control circuits for supplying electrical energy tothe motor illustrated in the references can also be applied to thevariable reluctance rotating machine of the present invention.

SUMMARY OF THE INVENTION The disc-type variable reluctance rotatingmachine of the invention is advantageous over other machines in that ithas a relatively simple construction, and its power rating can be variedmerely by changing the length of the rotating shaft and the number ofrotor and stator discs. Also, the design of the stator discs is uniquein that ithas an annular channel in which a winding is positioned. Ifdesired, the winding may be split into two parts that are positioned ina pair of channels in the stator disc. One of the advantages ofpositioning the winding in a channel arises from the relationship of thechannel with the rotor, which permits the winding to be easily cooled.

The variable reluctance rotating machine of the invention comprises aframe including a pair of end plates parallel to and spaced from oneanother. A shaft is rotatably journaled in the end plates for rotationabout its axis. At least one stator discis positioned intermediate theend plates and is supportedthereby. The stator disc has a centralopening therein through which the shaft passes. The stator disc includesa stator ring made from a non-magnetic material. The stator ring has anannular channel therein that is concentric with the axis of the statorring, and it also has a plurality of equally-spaced inner openingsextending axially therethrough on the radially inward side of theannular channel. An equal plurality of equally spaced outer openingsextend axially through the stator ring on the radially outer side of theannular channel. The outer openings are in radial alignment,respectively, with the inner openings. Inner and outer stator discinserts, made from a magnetic material, are positioned in each of theinner and outer openings in the stator ring. A

helical winding is positioned in the annular channel in the stator ring.

The rotating machine also includes at least one rotor disc positionedbetween one of the end plates and the stator disc. The rotor disc isattached to the shaft of the machine for rotation therewith. The rotordisc includes a rotor ring made from a non-magnetic material. It has aplurality of equally-spaced slots which extend in a radial direction.Rotor inserts, made from a magnetic material, are positioned in each ofthe slots to permit them alternately to come into and to go out of axialalignment with the inner and outer stator disc inserts when the shaftand rotor disc are rotated.

Preferably, the machine of the invention includes a plurality of stator.discs and a plurality of rotor discs, the rotor discs exceeding by onethe number of stator discs. The stator discs are positioned in spacedlocations along the axis of the machine. The rotor discs are positionedbetween and adjacent to the various stator discs.

Where the machine is provided with a plurality of rotor discs and statordiscs, it may be used in multiphase operation. This may beaccomplishedby the axial misalignment of the inner and outer stator disc inserts inone of the stator discs with respect to such inserts in another of thestator discs. 1

Reference has been made, and will be made hereinafter, to inner andouter stator disc inserts and to rotor disc inserts made from a magneticmaterial. The term magnetic material as used herein refers to amaterial'having a permeability substantially greater than thepermeability of free space.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of one-halfof a disc-type variable reluctance rotating machine constructed inaccordance with the invention;

FIG. 2 is a partial pictorial view of a stator disc for the machine ofFIG. 1;

FIG. 3 is a partial pictorial view of a rotor disc for the machine ofFIG. 1; and

FIG. 4 is an alternate construction for a stator disc for the machine ofFIG. 1.

DETAILED DESCRIPTION OF THE INVENTION With reference now to the drawingsand to FIGS. 1, 2, and 3 in particular, there is shown a disc-typevariable reluctance rotating machine designated generally by the numeral10.

The rotating machine 10 includes a frame structure including a pair ofend plates 12 and 14. In the form of the machine shown, these end platesare made from a non-magnetic material, such as fabric-reinforcedphenolic. Other material such as non-magnetic stainless steel may alsobe used. A shaft 16 is journaled in the end plates Hand 14 for rotationabout its own axis by means of ball bearings 18 and 20. A nut 22threaded on the shaft 16 and a bearing retainer 24 hold the inner race26 of the ball bearing 18 in position. The bearing 20 has an inner race28 that is held in position in a similar manner by the nut 30 andbearing retainer 32. The outer race 34 of the bearing 20 is held inposition by a bearing adapter 34 and a bearing retainer 36. Preferably,the shaft 16 and the associated bearings 18 and 20 and the retainerstherefor are made from nonmagnetic material, such as non-magnetic steel.

The variable reluctance machine includes a plurality of stator discs 38,40, 42 and 44. The stator discs are supported by the frame structureincluding the end plates 12 and 14 by means of tie rods 46. The statordiscs 38, 40, 42 and 44 are equally spaced between the end plates 12 and14 by means of spacers 48, 50, S2, 54

V and 56.

The construction of the stator discs 38, 40, 42 and 44 is shown indetail in FIG. 2. From FIG. 2,'it may be seen that the stator discsinclude a stator ring 58 that is made from a non-magnetic material, suchas fabric-reinforced phenolic. The stator ring 58 has an annular channel60 therein that is concentric with the axis of the stator ring and,also, with the axis of the shaft 16. In addition, the stator ring 58 hasa plurality of equallyspaced openings 62 extending in an axial directiontherethrough on the radially inward side of the annular channel 60.Similarly, the stator ring 58 has an equal plurality of openings 64extending in an axial direction on the radially outward side of theannular channel 60. The openings 62 and 64 are inradial alignment withone another. The inner openings 62 have laminated ferromagnetic innerstator disc inserts 66 positioned within them, and the outer openings 64have laminated ferromagnetic outer stator inserts 68 positioned withinthem. A helically wound winding 70, shown to the right in FIG. 2 forpurposes of clarity, is positioned in the annular channel 60. Thewinding 70 preferably is made from aflat conductive strip, but it mayalso be wound from a wire of circular or other cross-section. The leadsfrom the winding 70 may exit from the stator disc through a path 72provided in the stator ring.

With reference once again to FIG. 1, it may be seen that the variablereluctance machine includes a rotor assembly 74. The rotor assembly 74includes rotor discs 76, 78, 80, 82, and 84. A rotor support ring 86 ispositioned between rotor discs 76 and 78, and another rotor support ring88 is positioned between rotor discs 82 and 84. The rotor support rings86 and 88 are attached to the shaft 16 by any suitable means to enableit to rotate therewith. Spacers 90 are positioned between the rotordiscs 78 and 80 and between the rotor discs 80 and 82. Thus, it isapparent that the rotor assembly including the rotor discs, spacers, androtor support rings will rotate with the shaft '16. The rotor discs 76,78, 80, 82 and 84 move, respectively, within the spaces formed betweenthe end plate 12 and the stator disc 38, between the stator discs 38 and40, between the stator discs 40 and 42, between the stator discs 42 and44, and between the stator disc 44 and the end plate 14.

A plurality of tie rods 92 are provided to hold the rotor assembly 74together. It should be noted that the rotor discs exceed by one thenumber of stator discs.

The construction of the rotor discs 76, 78, 80, 82 and 84 may best beseen in FIG. 3. The rotor discs include a rotor ring 94 which has aplurality of radially extending and 44. The construction shown in FIG. 4differs from that in FIG. 2 in that there are two annular channels and102 in a stator ring 104. This is advantageous in that a split windingmay be used. Preferably, this split winding is comprised of twohelically wound flat conductive strips 106 and 108, which are assembledwith the stator disc 104 in the annular channels 100 and 102,respectively.

The operation of the variable reluctance rotating machine will now bedescribed in connection with FIGS. 1 through 3. With respect to thisdescription, it should be appreciated that when there is current in thewindings 70 of stator discs 38, 40, 42 and 44, magnetic flux is producedwhich is illustrated by the broken line paths 110, 112, 114, and 116,respectively.

As depicted in FIG. 1, the rotor disc inserts 98 are in axial alignmentwith the inner stator disc inserts 66 and the outer stator disc inserts68. Because these rotor disc and stator disc inserts are made from amagnetic material, it is apparent that the reluctance of the magneticpaths around the windings 70 is at a minimum when the rotor assembly 74is in this position. However, as the rotor assembly 74 is rotated, thereluctance of the magnetic paths 110, 112, 114, and 116 increases untilthe time when the rotor disc inserts 98 are midway between the inner andouter stator disc inserts 66 and 68. Continued rotation of the rotorassembly 74 causes the reluctance of the magnetic circuits to decreaseuntil the minimum reluctance is achieved when the rotor disc inserts andstator disc inserts are once again in axial alignment. Thus, the rotordisc inserts alternately come into and go out of axial alignment withthe stator disc inserts as the rotor assembly 74 is rotated.

If current is made to flow in the windings 70 during intervals ofdecreasing magnetic reluctance, and if a lesser quantity or no currentflows in the windings 70 during intervals of increasing reluctance, thenthe rotor assembly 74 will continue to rotate and electromechanicalenergy conversion will have taken place. The rotor assembly 74 willcontinue to rotate because a torque is produced tending to draw therotor disc inserts 98 toward the stator disc inserts 66 and 68. Thistorque is the result of the tendency of a magnetic circuit to produce aforce to minimize the reluctance of the magnetic circuit. This torquemay also be thought of as the result of the attractive forces betweennorth poles and south poles.

The variable reluctance machine illustrated in FIG. 1 is a single-phasemachine, and it may not have sufficient starting torque to producecontinued rotation of the rotor assembly 74. This would occur, forexample, if the rotor assembly 74 were initially stationary with therotor disc inserts 98 in axial alignment with the stator disc inserts 66and 68. This disadvantage may be overcome by the use of a multi-phaseconstruction for the variable reluctance rotating machine. This may beaccomplished by the axial misalignment of the inner and outer statordisc inserts 66 and 68 of one of the stator discs with respect to suchinserts in another of the stator discs. For example, the inner and outerstator disc inserts 66 and 68 of the stator discs 38 and 42 could beaxially misaligned with such inner and outer inserts in the stator discs40 and 44. In such case, the magnetic paths 110 and 114 could not have aminimum reluctance at the same time as the magnetic paths 112 and 1 16.Therefore, a starting torque could be produced by the application ofwinding current to the windings 70 of stator discs 38 and 42 or to thewindings 70 of stator discs 40 and 4 4. A better understanding ofmulti-phase disc-type variable reluctance rotating machine design maybeobtainedby reference to the aforementioned patents and patentapplications.

A functional variable reluctance rotating machine constructed inaccordance with the invention need only include one stator disc and onerotor assembly, but, preferably, two rotor discs would be used with thetwo rotor discs being positioned adjacent to and on opposite sides ofthe stator disc. Of course, a greater number of stator and rotor discsmaybe used if desired.

The machine of the invention can be operated as a pulsed-currentmachine, or it can be operated as an AC synchronous machine if means areprovided for bringing the shaft and rotor discs up to synchronous speed.This is necessary because the machine lacks starting torque whenoperated with AC.

Basedupon the foregoing description of the invention, what is claimedand desiredto be protected by Letters Patent is: v

l. A- variable reluctance rotating machine, which a, a frame including apair of end plates parallel to and spaced from one another;

b. a shaftrotatably journaled in said rotation about its axis;

c. a'stator disc positioned intermediate said end plates and supportedby said frame, said stator disc comprising a stator ring through whichsaid shaft passes, said stator ring being made from a nonmagneticmaterial and having an annular channel therein concentric with the axisof said stator ring, said stator ring also having a plurality ofequallyspaced inner openings extending axially therethrough on theradially inward side of said channel and an equal plurality ofequally-spaced outer openings extending axially therethrough on theradially outward side of said channel, said outer openings being inradial alignment, respectively, with said inner openings; a helicalwinding positioned in said annular channel in said stator end'plates forring; and inner and outer stator disc inserts, made from magneticmaterial, positioned in each of said inner and outer openings in saidstator rings; and

d. a rotor disc positioned between one of said end plates and saidstator disc, said rotor disc being attached to said shaft for rotationtherewith, said rotor disc comprising a rotor ring, made from anon-magnetic material and having a plurality of equally-spaced radiallyextending slots therein, and rotor inserts, made from a magneticmaterial and positioned in each of said slots to permit them alternatelyto come into and go out of axial align-.

ment with said inner and outer stator disc inserts when said shaft androtor disc are rotated. 2. A variable reluctance rotating machine inaccordance with claim 1, which further comprises a a second rotor dischaving a structure as defined in (d) of claim 1, said second rotor discbeing attached to said shaft for rotation therewith and being positionedbetween said stator disc and the other of said end plates.

3. A variable reluctance rotating machine in ac-. cordance with claim 1,wherein said stator disc includes a second annular channel thereinconcentric with the axis of said stator ring and wherein said statordisc further includes a second helical winding positioned in said secondannular channel in said stator ring 4. A variable reluctance rotatingmachine in accordance with claim 2, wherein said stator disc furtherincludes a second annular channel in said stator ring concentric withthe axis of said stator ring and wherein said stator disc furtherincludes a second helical winding positioned in said second annularchannel in said stator ring. I

5. A variable reluctance rotating machine, which comprises:

a. a frame including a pair of end plates parallel to and spaced fromone another; i

b. a shaft rotatably journaled in said end plates for rotation about itsaxis; r a plurality of stator discs equally-spaced from one another inanaxial direction and positioned intermediate saidv end plates andsupported by said frame, eachof said stator discs comprisinga statorring through which said shaft passes, said stator ring being made from anon-magnetic material and having an annular channel therein concentricwith the axis of said stator ring, said stator ring also having aplurality of equally-spaced inner openings extending axiallytherethrough on the radially inward side of said channel and an equalplurality of equally-spaced outer openings extending axiallytherethrough on the radially outward side of said channel, said outeropenings being in radial alignment, respectively, with said inneropenings; a

helical winding positioned in said annular channel in said stator ring;and inner and outer stator disc inserts, made from magnetic material,positioned in each of said inner and outer openings in said stator ring;and

d. a plurality of rotor discs, exceeding by one the number of saidstator discs, said stator discs being positioned between said rotordiscs and said rotor discs being attached to said shaft for rotationtherewith, each of said rotor discs comprising a rotor ring, made from anon-magnetic material and having a plurality of equally-spaced radiallyextending slots therein, and rotor inserts, made from a magneticmaterial and positioned in each of said slots to permit them alternatelyto come into and to go out of axial alignment with said inner and outerstator disc inserts when said shaft and rotor disc are rotated.

6. A variable reluctance rotating machine in accordance with claim 5,wherein said inner and outer stator disc inserts of at least one of saidstator discs are misaligned with respect to such inserts in another ofsaid stator discs.

7. A variable reluctance rotating machine in ac-- cordance with claim 5,wherein at least one of said stator discs further includes a secondannular channel in its stator ring, said second annular channel beingconcentric with the axis of said stator ring, and a second helicalwinding positioned in said second annular channel in said stator ring.

'A variable reluctance motor in accordance with respect to such insertsin another of said stator discs.

A variable reluctance rotating machine, which comprises:

a frame including a pair of end plates parallel to and spaced from oneanother;

a shaft rotatably joumaled in said end plates for rotation about itsaxis;

a plurality of stator discs equally-spaced from one another andpositioned intermediate said end plates and supported by said frame,each of said stator discs comprising a stator ring through which saidshaft passes, said stator ring being made from a non-magnetic materialand having an annular channel therein concentric with the axis of saidstator ring, said stator ring also having a plurality of equally-spacedinner openings extending axially therethrough on the radially inwardside of said channel and an equal plurality of equally-spaced outeropenings extending axially therethrough on the radially outward side ofsaid channel, said outer openings being in radial alignment,respectively, with said inner openings; a helical winding positioned insaid annular channel in said stator ring; and inner and outer statordisc inserts, made from magnetic material, positioned in each of saidinner and outer openings in said stator ring; and

. a rotor assembly, said rotor assembly comprising a pair of rotorsupport rings attached to said shaft for rotation therewith and aplurality of equallyspaced rotor discs supported by said rotor supportrings and exceeding by one the number of said stator discs, said statordiscs being positioned between said rotor discs, and each of said rotordiscs including a rotor ring, made from a non-magnetic material andhaving a plurality of equallyspaced radially extending slots therein,and rotor inserts, made froma magnetic material and positioned in eachof said slots to permit them alternately to come into and go out ofaxial alignment with said inner and outer stator disc inserts when saidshaft and rotor assembly are rotated.

1. A variable reluctance rotating machine, which comprises: a. a frameincluding a pair of end plates parallel to and spaced from one another;b. a shaft rotatably journaled in said end plates for rotation about itsaxis; c. a stator disc positioned intermediate said end plates andsupported by said frame, said stator disc comprising a stator ringthrough which said shaft passes, said stator ring being made from anon-magnetic material and having an annular channel therein concentricwith the axis of said stator ring, said stator ring also having aplurality of equally-spaced inner openings extending axiallytherethrough on the radially inward side of said channel and an equalplurality of equally-spaced outer openings extending axiallytherethrough on the radially outward side of said channel, said outeropenings being in radial alignment, respectively, with said inneropenings; a helical winding positioned in said annular channel in saidstator ring; and inner and outer stator disc inserts, made from magneticmaterial, positioned in each of said inner and outer openings in saidstator rings; and d. a rotor disc positioned between one of said endplates and said stator disc, said rotor disc being attached to saidshaft for rotation therewith, said rotor disc comprising a rotor ring,made from a non-magnetic material and having a plurality ofequally-spaced radially extending slots therein, and rotor inserts, madefrom a magnetic material and positioned in each of said slots to permitthem alternately to come into and go out of axial alignment with saidinner and outer stator disc inserts when said shaft and rotor disc arerotated.
 2. A variable reluctance rotating machine in accordance withclaim 1, which further comprises a second rotor disc having a structureas defined in (d) of claim 1, said second rotor disc being attached tosaid shaft for rotation therewith and being positioned between saidstator disc and the other of said end plates.
 3. A variable reluctancerotating machine in accordance with claim 1, wherein said stator discincludes a second annular channel therein concentric with the axis ofsaid stator ring and wherein said stator disc further includes a secondhelical winding positioned in said second annular channel in said statorring.
 4. A variable reluctance rotating machine in accordance with claim2, wherein said stator disc further includes a second annular channel insaid stator ring concentric with the axis of said stator ring andwherein said stator disc further includes a second helical windingpositioned in said second annular channel in said stator ring.
 5. Avariable reluctance rotating machine, which comprises: a. a frameincluding a pair of end plates parallel to and spaced from one another;b. a shaft rotatably journaled in said end plates for rotation about itsaxis; c. a plurality of stator discs equally-spaced from one another inan axial direction and positioned intermediate said end plates andsupported by said frame, each of said stator discs comprising a statorring through which said shaft passes, said stator ring being made from anon-magnetic material and having an annular channel therein concentricwith the axis of said stator ring, said stator ring also having aplurality of equally-spaced inner openings extending axiallytherethrough on the radially inward side of said channel and an equalplurality of equally-spaced outer openings extending axiallytherethrough on the radially outward side of said channel, said outeropenings being in radial alignment, respectively, with said inneropenings; a helical winding positioned in said annular channel in saidstator ring; and inner and outer stator disc inserts, made from magneticmaterial, pOsitioned in each of said inner and outer openings in saidstator ring; and d. a plurality of rotor discs, exceeding by one thenumber of said stator discs, said stator discs being positioned betweensaid rotor discs and said rotor discs being attached to said shaft forrotation therewith, each of said rotor discs comprising a rotor ring,made from a non-magnetic material and having a plurality ofequally-spaced radially extending slots therein, and rotor inserts, madefrom a magnetic material and positioned in each of said slots to permitthem alternately to come into and to go out of axial alignment with saidinner and outer stator disc inserts when said shaft and rotor disc arerotated.
 6. A variable reluctance rotating machine in accordance withclaim 5, wherein said inner and outer stator disc inserts of at leastone of said stator discs are misaligned with respect to such inserts inanother of said stator discs.
 7. A variable reluctance rotating machinein accordance with claim 5, wherein at least one of said stator discsfurther includes a second annular channel in its stator ring, saidsecond annular channel being concentric with the axis of said statorring, and a second helical winding positioned in said second annularchannel in said stator ring.
 8. A variable reluctance motor inaccordance with claim 7, wherein said inner and outer stator discinserts in at least one of said stator discs are misaligned with respectto such inserts in another of said stator discs.
 9. A variablereluctance rotating machine, which comprises: a. a frame including apair of end plates parallel to and spaced from one another; b. a shaftrotatably journaled in said end plates for rotation about its axis; c. aplurality of stator discs equally-spaced from one another and positionedintermediate said end plates and supported by said frame, each of saidstator discs comprising a stator ring through which said shaft passes,said stator ring being made from a non-magnetic material and having anannular channel therein concentric with the axis of said stator ring,said stator ring also having a plurality of equally-spaced inneropenings extending axially therethrough on the radially inward side ofsaid channel and an equal plurality of equally-spaced outer openingsextending axially therethrough on the radially outward side of saidchannel, said outer openings being in radial alignment, respectively,with said inner openings; a helical winding positioned in said annularchannel in said stator ring; and inner and outer stator disc inserts,made from magnetic material, positioned in each of said inner and outeropenings in said stator ring; and d. a rotor assembly, said rotorassembly comprising a pair of rotor support rings attached to said shaftfor rotation therewith and a plurality of equally-spaced rotor discssupported by said rotor support rings and exceeding by one the number ofsaid stator discs, said stator discs being positioned between said rotordiscs, and each of said rotor discs including a rotor ring, made from anon-magnetic material and having a plurality of equally-spaced radiallyextending slots therein, and rotor inserts, made from a magneticmaterial and positioned in each of said slots to permit them alternatelyto come into and go out of axial alignment with said inner and outerstator disc inserts when said shaft and rotor assembly are rotated.